This invention relates to an improved solution containing luprostiol and 1,2-propanediol.
Solutions of luprostiol (7.alpha.-(2-(3-(3-chlorophenoxy)hydroxypropylthio)-3.alpha., 5.alpha.-dihydroxycyclopentyl)-5-heptenoic acid) in 1,2-propanediol are disclosed in Canadian Patent Specification No. 1,142,434. They are used in particular, as injection solutions in medical treatment of humans and, above all, in veterinary medicine, for luteolysis, for synchronizing estrus or for inducing labor, for example in the case of horses, cattle, pigs, sheet and goats.
Disadvantages have been found in using the known solutions. In particular, problems are caused by the high viscosity, which renders drawing and injection considerably difficult, particularly at low temperatures such as prevail in the winter half-year, which is the principal season for practical use. Furthermore, solutions of the free acid luprostiol are unstable to a limited extent, since esters are formed from the acid and the solvent as the result of acid autocatalysis.